Password Strength Entropy Calculator
Reviewed by Hamza Gujjar, Algorithm Architect & Software Developer
Last updated: July 28, 2026Password Strength Entropy Calculator
How strong is a password, technically speaking? This calculator computes entropy in bits, the standard measure of password unpredictability.
Entropy (bits) = Password Length x log2(Character Set Size)
Example
A 12-character password using the full 95-character printable ASCII set:
Entropy = 12 x log2(95) = 78.8 bits - Strong
What Entropy Actually Measures
Entropy measures password unpredictability in bits - each additional bit of entropy doubles the number of possible combinations an attacker attempting a brute-force guess would need to try before finding the correct password.
Why Length Beats Character Variety
This formula is exactly why increasing password length has a much larger security impact than adding a slightly larger character set at the same length - one additional character multiplies total combinations by the full character set size, while expanding the character set only multiplies by a smaller factor.